Known devices of this type can be of relatively simple structure when they are designed for use with rims that can be disassembled or with special rims, however when they are to be fitted on standard rims (made as a single piece) having fixed lateral flanges for holding the beads of a tire, such devices are necessarily made of a plurality of parts each in the form of an arc of a circle, which parts are connected together end to end by mechanical link means using screws, eccentric means, etc. . . . so as to form a running ring which can be clamped onto the rim and which can be dismantled and withdrawn from the rim in spite of its lateral flanges.
These linking and clamping means are the source of considerable drawbacks since handling them is awkward and sometimes lengthy (it is necessary to place the hands and/or tools between the rim and the tire), yet such handling can be critical since poor clamping of the running ring on the rim can cause it to be destroyed quickly when running on a flat tire. Furthermore, the link means are sensitive to shock and are subjected in use to considerable forces which vary over time, thereby giving rise to fatigue phenomena that can cause them to break quite quickly, thereby destroying the run-flat device.
For fitting to mass-produced vehicles, run-flat devices must be capable of being fitted on standard wheel rims, i.e. on rims that are made as a single piece with lateral flanges.
For this purpose, devices have already been proposed that are formed by at least two circularly-arcuate elements which are connected end to end by link means, e.g. using screws, eccentrics, etc., in order to form a continuous ring which is clamped onto the rim and which can be fitted to and stripped from the rim in spite of its lateral flanges.
It has been found that such link means are often the cause of run-flat devices being destroyed prematurely for various reasons (poor clamping, sensitivity to shock, to vibration, fatigue phenomena, etc. . . . ).